Setting a timelapse with several keyframes. I did some settings of each keyframe in LR and saved metadatas of these keyframes.
Then I do "Reload" and "Auto transition" and "visual preview" (there is no save button in this version 5)
But EACH KEYFRAME IS BRIGHTER THAN EVERY OTHER PICTURE OF THE TIME LAPSE, you see it on your screen and you read it in the "visual lum" column where the value of the keyframe is higher than the previous and the next ones.
I thought first it was specific at the visual preview process but after reading the metadatas of all frames in LR it is the same problem. I can't see any difference in the LR settings between a keyframe and the next (or the previous) frame when visually the keyframe is brighter (and the visual lum is higher)

I did several attempts, clearing every metadatas and lrt folder...

and I came to this observations :
you create keyframes and then you do the HG Wizard, but for each keyframe the HG value is out of the "curve" as if there would be some strange mix between HG value and Keyframe setting

For now I resolve the problem by entering manually for each keyframe a HG value more "in the curve"...

Since it's not my own computer I didn't upgrade upgrade to 5.1.0 where you may have already deal with this problem.

More precisions :
in fact it's not during the first phase that the problem appears
it's after doing correction of the keyframes in LR and when you reload that, then, the "HG Lum Leveling" value behave strangely

Sorry for the wrong choice of forum.
I used 2 of the four dots of the linear gradients (and I did a test whithout gradients at all with the same problem)
I didn't use presets
I didn't use dehaze
I didn't use any stamp nore brushes

I only used basic color tone setting, detail settings and two linear gradients

I will do some test with one setting after the other to try to find which one is screwing up the process.

The problem come from pasting developing settings in LR. When I copy a setting from a keyframe there is a window to choose which settings you want to select. Generally I select "check all" but in fact it select then the "HG Lum Leveling" value despite the fact this value doesn't appear in the list of check box, so when I paste the settings to another keyframe, it paste also the "HG Lum Leveling" value that could not match at all in the continuity of HG.
I did another test where I select only the few settings necessary : white balance, basic tone, noise reduction and local adjustments
but I am still pasting the HG Lum value
It seems then that, as soon as you copy any developing settings, it copy also the HG Lum value...

one more step in my investigation :
after several test with each setting the conclusion is :
IN LR WHEN YOU COPY AND PASTE "LOCAL ADJUSTMENTS" IT COPY AND PASTE ALSO THE HG LUM LEVELING VALUE
and in the frame from which I copy these local adjustments I only used the pre-generated adjustments.